Additive Manufacturing (AM) is a unique fabrication method that enables complex and flexible geometry designs for a wide range of components, including two-phase thermal management components like heat pipes. This project focuses on titanium-ammonia heat pipes used for future space electronic payloads like satellites and comparing their performance against conventionally manufactured heat pipes with screen mesh capillary wicks. AM increases the ability to integrate components into chassis elements, directly cool electronics components, and improve the functionality against gravity which eases ground testing. Both AM and screen mesh wick structures offer enhanced evaporator heat flux versus aluminum-ammonia, grooved wick heat pipes, enabling direct thermal management of electronics components.
Prospective telecommunications satellite payloads are expected to release a step-increase in power dissipation, requiring innovative thermal management techniques. Ammonia heat pipes are heavily deployed at platform level within radiator panels, as surface mounted heat pipes and as thermal links. However, system designers cannot integrate them into electronics chassis for direct micro-electronic cooling due to the low evaporator heat flux limit of extruded axially grooved capillary wicks, low maximum operating temperature, and inability to function against gravity on ground test. Novel gravity-friendly heat pipes offer a means of direct thermal management of future payloads.
This project identified, developed, and completed acceptance testing on a new heat pipe technology that extends the functional temperature range of ammonia working fluid heat pipes. It also helped overcome challenges during ground-testing of non-gravity friendly heat pipe by implementing new wick structures that enable functionality against gravity. The project investigated novel working fluid and wall materials combinations (Figure 3), investigated enhanced screen-mesh capillary wick structures, and developed a first generation of additive manufactured heat pipes. The goal of these new AM heat pipes is to enable integration of the chassis structure and enable direct thermal management of microprocessors.